KR100550706B1 - Film for multilayer security document lamination - Google Patents

Abstract

The present invention relates to a laminated multilayer film substrate having an oriented polypropylene layer and at least one high density polyethylene layer on each side of the oriented polypropylene layer, for use in the preparation of pre-weakened banknotes to eliminate delamination. . The resulting film exhibits good embossability, full folding characteristics and other properties and is difficult to forge, making it well suited for the manufacture of banknotes and other security documents.

Description

FILM FOR MULTILAYER SECURITY DOCUMENT LAMINATION}             

FIELD OF THE INVENTION The present invention relates to multilayer films for use in the manufacture of paper-like products, such as security documents and bank notes, including traveler's checks and bank checks, and methods of making the same. More specifically, the present invention relates to a multilayer film having the characteristics of high quality paper typically used in the production of banknotes and security documents.

In the manufacture of bank notes, security documents and the like, rag paper has been used for over 300 years. As is well known, lag has many desirable properties for such applications, including complete foldability, tear resistance, printability, embossability and inability to peel.

This highly desirable property is characterized as follows: Complete deadfold is the ability of a substrate to remain folded without being folded or folded. Tear resistance is the ability of a substrate to be resistant to tears and tears already disclosed, or to tears and tears not yet disclosed. Printability is the ability of the substrate to absorb and bind the inks used during the lithographic process. Embossing is the ability of a substrate to form raised images on banknotes or security documents created by deformation under the pressure of the intaglio printing process, at which point the elevation of the banknotes or security documents due to the intaglio ink remaining on the raised and deformed areas. The feel or feel of it appears. Inability to peel indicates that the entire layer cannot be separated after lamination. As will be appreciated, these properties combine to give the banknotes and the like a familiar feel and functionality.

With the development of color copiers and computer graphics scanners, counterfeiting of banknotes has increased considerably. While active programs are underway by major banknote manufacturers to make substrates safer through the use of transparent fringes, metal wires and optical variable devices (e.g., photochromic, stereographic and diffraction gratings), At present, these efforts do not appear to prevent counterfeiting.

The main suitability for standards of use in security documents is to ensure that the entries are not separated to produce the originals on each side of the document. Separation of banknotes is a major counterfeit tactic in developing countries. Tyvek ^R , a multi-layered security document, could not be used in the art because it could separate documents of the nonwoven with a simple tool in the art.

Plastic substrates provide major security properties if a transparent "window" is introduced into the banknote. This window can ensure that the scanner or color copier cannot copy the banknote. In addition, other security features may be incorporated into or on the banknote, including reverse printing of the banknote, to protect the security device and printed matter.

Australian patent 488,652 discloses an approach to the manufacture of security products, in particular banknotes, and describes the serious problems faced by conventional banknotes in counterfeiting. The banknotes disclosed in this patent include a substrate of opaque thermoplastic sheet material tightly bonded to a web of woven or nonwoven thermoplastic fibers, wherein the substrate is printed as needed and one or more optically variable security devices are mounted on the substrate. Combined. Fibrous webs have been used to impart durability, durability, and tear-strength to banknotes. If a security device is used, such as a ripple pattern, that varies with its light variability properties in the transmission of light, it is necessary to puncture the substrate, insert the device and bond the device in place with an additional layer of transparent plastic sheet material. There was.

Although the samples of banknotes formed in accordance with the disclosure of Australian patent 488,652 were performed most satisfactorily in terms of durability and security of conventional banknotes, the samples were found to be somewhat complex in construction and relatively high in production cost. In addition, when the transfer security device is stacked between layers in the substrate, a weak and highly stressed area is created that reduces both durability and security.

Other disclosures related to anti-counterfeiting techniques include US Pat. Nos. 4,095,217 and 4,281,208, which relate to the use of liquid crystal devices driven by photovoltaic devices such as solar cells or amorphous silicon materials.

U. S. Patent No. 4,472, 627 relates to currency or other deeds containing liquid crystal / photovoltaic devices that produce coded representations in response to artificial or ambient light. The device serves as an anti-counterfeit and a means by which a user can easily prove the value of a document containing the device.

U. S. Patent No. 4,536, 016 discloses a security indication, such as a banknote or identity document, comprising a sheet-like substrate made of a film of transparent biaxially oriented polymer coated with a layer of opaque and heat activated adhesive material. The opaque layer is applied in a manner that leaves transparent areas for the inspection of security devices (eg diffraction gratings) incorporated in the polymer film. The substrate may have a printed or other proven sign and is protected by a tightly bonded layer of transparent polymeric material.

The substrate used in US Pat. No. 4,536,016 is based on the use of oriented polypropylene (OPP). After printing a number of commemorative banknotes, it was found that plastic banknotes failed in three major areas, even if they met a number of requirements for listing banknotes. First of all, the OPP substrate is not fully folded, causing problems in that the film remains in either a flat or curved form, and breaks down the cash register and automatic processing equipment. Secondly, the OPP substrate is poor in tear resistance already disclosed in the processing of money, and very often results in flaws on the edges of banknotes, causing them to tear completely. Finally, OPP products do not exhibit the touch of paper currency because OPP is not well embossed and overcoated during the engraving process.

delete

Oriented high density polyethylene (HDPE) has been used in the area of plastic packaging. Such films which are biaxially oriented to greater than 6.5 times in both the machine direction (MD) and the transverse direction (TD) are described in British Patent No. 1,287,527. U.S. Patent No. 4,680,207 discloses an imbalanced biaxially oriented film of linear low density polyethylene (LLDPE) oriented less than 6 times in the machine direction, less than 3 times in the transverse direction and smaller than the machine direction. It is about.

U. S. Patent No. 5,618, 630 relates to a three-ply multilayer film structure for producing bank notes.

While the films described above present particular advantages over the prior art and generally appear to meet the requirements that led them to be devised, they are characterized by the high quality lag type paper typically used in the production of banknotes and security products. There is still a need for a providing film.

Accordingly, it is an object of the present invention to provide a multilayer film having the properties of high quality rag paper.

Another object of the present invention is to provide such a multilayer film that is easy to manufacture and extremely durable and has the full dead-fold properties of high quality paper.

Further, another object of the present invention is to provide a multilayer film in which the entire layer cannot be effectively separated without tearing.

Further, another object of the present invention is to provide a multilayer film having printability and embossing property of high quality paper.

It is a further object of the present invention to provide a multilayer film having a high degree of resistance to curling at high temperatures, for example higher than 150 ° F.

In addition, another object of the present invention is to provide a multilayer film suitable for the production of banknotes by making it difficult to peel off the ink from the banknotes so that the banknotes can be used for a long time. The film can achieve a high level of durability without covering the inked surface with a protective coating such as lacquer or polyurethane.

It is another object of the present invention to provide a multilayer film suitable for the production of banknotes, which is less likely to be counterfeit.

Other objects and advantages of the invention will be apparent to one of ordinary skill in the art upon reading this specification and the claims appended hereto.

The multilayer film of the present invention is a three-ply structure. One or more oriented polypropylenes (OPPs) are surrounded by one or more layers of HDPE on one of both sides of the OPP layer. The multilayer film of the present invention shows excellent performance in repeated folding tests. In addition, the multilayer film structures of the present invention have high tensile strength in both oriented and unoriented directions. The multi-layered structure of the present invention does not leave any residual amount even when wrinkled in the print window.

Multilayer films of the present invention have poor tear resistance in one or more layers of HDPE on either side of the OPP layer. Tear resistance in one direction is at least ten times greater than tear resistance in the other direction.

According to the invention, (a) the ratio of tear resistance already disclosed is greater than 10: 1 and comprises at least 50% by weight of high density polyethylene having an inner surface and an outer surface and having a density of at least 0.94 and substantially perpendicular to the first direction. An unbalanced biaxially oriented first layer oriented in at least the first direction to an extent that is at least three times smaller than the degree of orientation present in the second direction; (b) a second having an inner surface and an outer surface and comprising at least 90% by weight of polypropylene, oriented in at least a first direction at an orientation ratio of at least 4: 1, and substantially perpendicular to the first direction at an orientation ratio of at least 6: 1; Balanced biaxially oriented second layer; (c) a ratio of tear resistance already disclosed is greater than 10: 1 and comprises at least 50% by weight of high density polyethylene having an inner surface and an outer surface and having a density of at least 0.94, in a second direction substantially perpendicular to the first direction; An unbalanced biaxially oriented third layer oriented in at least the first direction to a degree at least three times less than the degree of orientation present; And (d) a laminating adhesive resin positioned between the inner surface of the layer of (a) and the inner surface of the layer of (c), wherein the second layer is laminated to the first layer and the third layer so that the third layer Wherein the first direction of orientation substantially coincides with the first direction of the first layer orientation, wherein the layer of (a) further comprises a surface of the propylene copolymer coextruded over its inner surface, thereby producing a banknote or security document. For use, a laminated multilayer film substrate is provided that is resistant to curling and symmetric in cross section.

In forming the multilayer film of the present invention one or more layers of the substrate comprise OPP. The use of OPP in the core shows high tensile properties and excellent performance in repeated folding tests. In addition, in the case of using the three-ply structure of the present invention, even after bending by hand, the print window does not have a residual amount.

It is preferable to use OPP in the core. However, other biaxially oriented polymers with comparable tensile strengths such as LLDPE, nylon or polyester can also be used. The OPP core is preferably free of any additives such as silicone and antistatic agents that are effective for adhesion to other layers.

In forming a multilayer film substrate for use in the production of banknotes and other security documents of the present invention, at least two layers of the substrate have a large proportion of HDPE having a density of at least 0.94, preferably at least 0.945, more preferably at least 0.96. It contains. These film layers may be a single HDPE resin, a mixture of HDPE resins, or other polymeric materials, such as LDPE, LLDPE, polypropylene, ethylene vinyl alcohol (EVOH) copolymers, ethylene propylene (EP) ) Copolymers or HDPE containing a small proportion of ethylene-propylene-butene-1 (EPB) copolymers, although a single HDPE resin or blend of HDPE resins may be Particularly preferred in practice.

If a blend of HDPE polymers is used, the blend may comprise two or more polymers, all of which preferably have a density of greater than 0.94. The blend of HDPE polymers comprises a large proportion of HDPE having a melt index of 0.6 to 1.2, and also at least one polymer having a different melt index.

Triblends may also be preferred. Suitable triple blends generally comprise from 50 to 98% by weight, preferably 84 to 96% by weight of HDPE having a density of greater than 0.96 and a melt index of 0.5 to 2.0; 1 to 25% by weight, preferably 3 to 8% by weight of HDPE having a density of at least 0.94 and a melt index of 0.1 to 0.5; 1 to 25% by weight, preferably 3 to 8% by weight HDPE having a density of at least 0.96 and a melt index of 2 to 8. Preferably, the minor component of the second HDPE polymer and the third HDPE polymer are present in equal amounts.

Particularly preferably, the film substrate of the present invention comprises (a) at least 50% by weight of HDPE having a density of at least 0.94 and is present in a second direction (eg TD) substantially perpendicular to the first direction. A first layer oriented in at least a first direction (eg, MD) to a degree at least three times smaller than the degree of orientation; (b) a second comprising at least 90% by weight of polypropylene, oriented in at least a first direction (eg, MD) at an orientation ratio of at least 3: 1, and substantially perpendicular to the first direction at an orientation ratio of at least 6: 1; A second layer oriented in a direction (eg, TD); And (c) at least 50% by weight HDPE having a density of at least 0.95, wherein the first direction (at least three times smaller than the degree of orientation present in the second direction (eg, TD) substantially perpendicular to the first direction); For example, a third layer oriented in MD), wherein the third layer is laminated to the film substrate such that the first direction of orientation of the third layer is substantially parallel to the first direction of orientation of the first layer. (Or matches).

A method of making an HDPE film having an unbalanced biaxial orientation is disclosed in US Pat. No. 4,870,122.

The film is produced and oriented in a conventional manner. The film is heated to its orientation temperature and first the MD orientation is applied between two sets of nip rolls, with the second nip roll rotating at a rate greater than the first nip roll in an amount equal to the desired draw ratio. The film is then heated and stretched laterally in a tenter frame for TD orientation. Typically, MD orientation is performed at 60-120 ° C. and TD orientation is performed at 110-145 ° C.

Although the degree of orientation in the first film direction is preferably at least three times smaller than the degree of orientation present in a direction substantially perpendicular to the first direction, each HDPE film layer is about 1.1 to 2.0 times in MD and about 6 to 12 times in TD. Particular preference is given to being oriented. It has been found that HDPE film layers can be produced with good quality at casting speeds of 110 fpm or less, corresponding to a line speed of 140 fpm (feet per minute) at an MD orientation of 1.25 times. In an alternative method, the degree of orientation in the first film direction may be at least three times greater than the degree of orientation present in the direction substantially perpendicular to the first direction. Even unoriented and blown HDPE can be used as the first and third layers, and also maintain some degree of complete foldability in the multilayer film substrate of the present invention.

In use, this degree of unbalanced orientation has an interesting effect on the HDPE component of the structure. The effect is manifested by visible ripples and striped appearance, the ripples being parallel to the transverse direction. If you zoom in at a low rate, you will see generally parallel stripes to the ripple and orientation directions of 5 to 30 discontinuous waves in each square centimeter of the HDPE film. This effect gives the film a slightly transparent appearance, and tends to appear slightly blurred when distant objects are observed through the film. This effect indicates that the layer is oriented in an unbalanced manner. High density polyethylenes contemplated for use in the practice of the present invention include those described in US Pat. No. 4,870,122.

For the OPP layer, the orientation is adjusted to provide essentially balanced tensile properties in both directions.

In order to achieve the desired surface properties required for the paper-like article of the invention, the HDPE can be obtained in any known manner, for example by coating or coextrusion before orientation or after one or two alignment treatments. One or more surface layers may be applied to the multilayer HDPE base material by coating. The surface layer can be any conventional material used for this purpose with polyolefin films, in particular polyethylene films. For example, in order to achieve a surface that is easy to compress, the polymer resin may be blended with fillers, fibers or pigments and the like if necessary. In addition, hollow films can be laminated to multilayer HDPE substrates to impart opaque properties of these structures to the films of the present invention as described in US Pat. Nos. 4,377,616, 4,632,869, 4,758,462 and other patent applications.

The layer of HDPE-containing (a) and (c) as described above are, for example, ethylene-propylene-butene-1 terpolymers provided on one or more sides thereof, preferably both on the inner and outer surfaces thereof. It may further comprise a copolymer polypropylene surface, such as a copolymer. In one embodiment, the surface itself may also include components similar to those in the adhesive resin used to laminate the layers of (a), (b) and (c). For example, LDPE may comprise 10 to 20% by weight of the surface, with the remainder being copolymer polypropylene.

Suitable adhesive-promoting primers that provide greater adhesion between the laminated surface, the opaque layer and the printing cap, such as polymers selected from the group consisting of polyethyleneimide, epoxy, polyurethane, and acrylic, are HDPE layers And between the coated surface. Primer compositions are disclosed in US Pat. Nos. 4,447,494 and 4,681,803.

It can also be appreciated that the substrate can be embossed, dyed, printed, documented or otherwise processed before or after lamination, which can be done on the inner or outer surface of the laminated layer, for example, the properties of banknotes, It can be used to visually and / or tactilely distinguish its importance or value. In addition, printing on the core is also a security feature. Any flexo or gravure printable ink, colored or machine readable inks such as IR, UV and magnetic inks can be used.

Lamination techniques that can be used to carry out the present invention are known in the art and include adhesive-bonding or cementing with, for example, laminated adhesive resins, preferably transparent agents; Solvent-bonding, where the mist of solvent is sprayed onto the surface to which they are bound together; Thermal lamination by heat-bonding to hot roll or compress the thermoplastic sheet; A cast-laminate in which one layer is cast over the second layer and the second layer forms a substrate; Or extrusion lamination or stretch-lamination used in calendering processes known in the art. Laminated adhesive resin is stronger than the outer surface layer.

Particular preference is given to using adhesive resins that are solvent-free or 100% solid, such as WD4110, a two-part polyurethane resin available from H.B. Fuller Co. 100% solid laminate adhesives are an effective alternative to solvent based adhesives. The 100% solid laminate adhesive imparts excellent transparency, improved printing, high bond strength and heat seal resistance to the multilayer film laminated structure of the present invention.

When incorporating a separate security device, such as an optically variable device (OVD), into the substrate, the device may be wrapped in a pouch attached to the substrate. On the other hand, the OVD itself can be introduced into or between layers (or two layers) of the laminated substrate, and it is not necessary to introduce physically separated devices into clearly defined pockets formed between the layers.

Any suitable security device can be used in the present invention, such as an device selected from the group consisting of OVDs, magnetic devices, electrical devices and rare earth element-containing devices, with OVD being particularly preferred.

As used herein, the term "optical variability" is used to mean any device that can be readily manufactured to easily change its appearance in a reversible, predictable, and reproducible manner. The appearance of the device may vary, for example, by body heat or hand pressure, changes in viewing angles and light conditions under which viewing can occur. The type of device envisioned by the present invention has a diffraction grating, a liquid crystal, a ripple pattern, and a transparent grid in the form of an overlapping and refracted lens such as a partially reflective and partially transparent Fresnel lens in space. Similar patterns produced by coatings, bi-refractive or polarizing layers, zone-plates, and the like, with or without cross diffraction, various interference patterns, and the like.

In general, optically-active devices having these characteristics are readily recognized by those of ordinary skill but are extremely difficult to reproduce with photographic and printing techniques. Moreover, producing any such device in a renewable type and incorporating it into a plastic laminate as described by the present invention may be beyond the reach of the majority of self-propelled counterfeiters. To obtain a product in the form of a flexible paper such as a banknote, it is desirable that the OVD itself is similar to the sheet, flexible and thin. It is also desirable that the device be compatible with the plastic materials used in the lamination to facilitate bonding and to mitigate reactive changes that occur over time.

According to the invention, one preferred type of OVD may be a reflective diffraction grating consisting of a metallized thermoplastic film embossed in a diffraction pattern. In order to prevent access to the embossed pattern for the purpose of illegal copying, in accordance with the present invention a layer of thermoplastic material on each side of the metallized film having a solubility characteristic similar to that of the metal layer is used for differential etching. It is desirable to make the separation very difficult. Another preferred device is a rippled pattern formed by fine lines reproducing a photograph or a dot pattern on each face of a thin film. The spacing of the dots and lines is so fine that they are easily produced so that they cannot be reproduced by printing techniques, and the ripple pattern can be displayed on a larger scale. Unique diffraction and ripple patterns are often desirable for use in banknotes, and the technique can be used to produce them by computer and photoreduction methods.

In producing small banknotes, the appropriate level of security against counterfeiting can only be obtained by providing a transparent "window" through the banknote. As described above, the window prevents the scanner or color copier from copying the banknote. In addition, other security features may be incorporated into or on banknotes, including reverse printing of banknotes to protect security devices and prints.

Similar to the films of the present invention, but "cross-oriented" films are susceptible to curling at temperatures higher than 150 ^° F. The crosslinked-oriented film has a second layer laminated on the film substrate such that the first direction (major direction) of the orientation of the second layer is substantially perpendicular to the first direction (major direction) of the orientation of the first layer. It is similar to the film of the present invention except that. The curling is believed to occur at high temperatures because each layer differs in shrinkage in the machine and transverse directions. Additional curling ease can occur when the coating or surface of the layer has a different shrinkage coefficient than the HDPE component of the layer. The imbalance shrinkage and its incidental curling can be avoided by offsetting the overall water-side properties of one layer by further laminating the same second layer as the first layer provided as a mirror image of the first layer. In other words, half of the layered film structure is a mirror image of another layer having a plane of symmetry along the horizontal centerline of the layered film structure cross section. This provides a layered film structure that is symmetrical in cross section. Examples of such films include films of structures such as ABA, ABBA, ABCCBA, ABCDCBA, each letter representing a film layer, surface, coating or adhesive layer. The layered film structure that is symmetrical in cross section is necessarily a "parallel-oriented" structure, ie a structure in which the main direction of orientation of the first layer is parallel with the main direction of orientation of the second layer in order to satisfy the mirror image requirements. The structure provides a symmetrical structure in which the opposite shrinkage forces cancel each other to a considerable extent. However, the bilayer parallel structure tends to have poor tearing properties in one direction (eg TD), where two TD oriented films are used.

It has also been found that by using a resin that is 100% solid as the laminated adhesive resin used, the orientation effect resulting from the lamination process is improved, resulting in a multilayer film showing curling resistance and improved chemical resistance.

In the present invention, the layer containing at least one HDPE has a weakened tear resistance in one direction to such an extent that the layer is considerably weaker than the laminating additive resin and the OPP containing core layer. When attempting to exfoliate the structure for forging purposes, only a small amount of strips of the outer printed HDPE containing layer will be removed. The entire HDPE containing layer cannot be removed.

HDPE containing layers can be teared using process conditions during the manufacturing process. In addition, micropores by laser technique and / or nicking may weaken the HDPE containing layer. The micropores are diagonal or unidirectional, for example in the range of 50 to 300 dpi (dots per inch).

In addition, the HDPE layer can be teared through the addition of incompatible additives that fiber or break the layer during orientation. Suitable incompatible polymer additives that affect crystallization include polyester (PET), polybutylene terephthalate (PBT), polystyrene, or mixtures thereof. Generally 1-10% by weight, preferably 4-8% by weight, of incompatible additives is added to the HDPE layer (s). Fibrosis forms a region of oriented HDPE surrounding the long planar region of the incompatible polymer to form a low tear region.

The OPP core layer does not weaken and essentially provides the tensile properties and tear resistance of the structure as a whole.

The invention is further illustrated by the following non-limiting examples, in which all parts are parts by weight unless otherwise indicated.

Example 1

This example is suitable for making banknotes with good full fold characteristics, and shows the manufacture of a multilayer film substrate made according to the present invention.

Multilayer oriented film substrates having a 1.15 mil final thickness were prepared by coextrusion of HDPE and incompatible copolymers with copolymer polypropylene surfaces on both sides. The HDPE layer contains 94% HDPE [Oxychem M-6211] and 6% polystyrene, available from Occidental Chemical Corp., Dallas, Texas, with a density of 0.96 and a melt index of 1.0. Include. The copolymer polypropylene surface is 90% by weight of Chisoso, EPB-1 terpolymer (available from Kiso Corporation, Japan) and Nobil LKA-753 (LDPE, Norwalk, CT). Commercially available from Mobil Chemical Co.]. While HDPE constituted 90% by weight of the film layer of (a) produced, the surface comprised 10% by weight (5% by weight on each side). The film of (a) is then oriented 1.4 times in MD at 115 ° C. and 6-12 times in TD at 115-140 ° C., for example 10 times in a tenter frame.

The layer of (a) is a solid laminated with 100% adhesive to the OPP layer of (b) described below using WD4110, a two-part polyurethane resin commercially available from H. B. Fuller Corporation.

The OPP layer is 1.15 mil final thickness fabricated using FINA 3371 homopolymer polypropylene in the core at 109 reference units and two surface layers of Lyyondell M60-30 HDPE at 3 reference units. Had The MG60-30 may contain process aids and / or surface modifiers.

The two-ply layer is another 100% solid laminated to another HDPE layer by the puller WD4110 described above.

Example 2

Example 1 was repeated using WD4006, an aqueous adhesive available from H. B. Fuller Corporation as an extrusion lamination adhesive, and 4% polybutylene terephthalate as an incompatible polymer, on both HDPE layers.

Example 3

Example 1 was repeated with Chevron 1017 commercially available from Chevron and the micropores of the HDPE layer at the time of lamination as the extrusion laminate adhesive, without incompatible polymers. The micropores are diagonally patterned through the two layers at an angle of 45 ^{o with a} 1/4 inch gap between the holes.

While the invention has been described in terms of preferred embodiments, it will be readily apparent to one skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention. Such modifications and variations are considered to be within the scope and scope of the appended claims.

Claims (21)

A laminated multilayer film substrate that is curling resistant and cross-sectional symmetric for use in the manufacture of bank notes or security paper, (a) an agent having a ratio of tear resistance already disclosed that is greater than 10: 1 and which has an inner surface and an outer surface and comprises at least 50% by weight of high density polyethylene (HDPE) having a density of at least 0.94 and is substantially perpendicular to the first direction; An imbalanced biaxially oriented first layer oriented in at least the first direction to a degree at least three times less than the degree of orientation present in the two directions; (b) a second having an inner surface and an outer surface and comprising at least 90% by weight of polypropylene, oriented in at least a first direction at an orientation ratio of at least 4: 1, and substantially perpendicular to the first direction at an orientation ratio of at least 6: 1; Balanced biaxially oriented second layer; (c) a ratio of tear resistance already disclosed is greater than 10: 1 and comprises at least 50% by weight of high density polyethylene having an inner surface and an outer surface and having a density of at least 0.94, in a second direction substantially perpendicular to the first direction; An unbalanced biaxially oriented third layer oriented in at least the first direction to a degree at least three times less than the degree of orientation present; And (d) a laminate adhesive resin positioned between the inner surface of the layer of (a) and the inner surface of the layer of (c), wherein The second layer is laminated to the first layer and the third layer such that the first direction of the third layer orientation substantially coincides with the first direction of the first layer orientation, and the layer of (a) is coextruded over its inner surface A laminated multilayer film substrate that is curl resistant and transversely symmetric, further comprising a copolymer surface. The method of claim 1, A laminated multilayer film substrate that is curling resistant and transversely symmetric, wherein both the layers of (a) and (c) further comprise an incompatible polymer. The method of claim 1, A laminated multilayer film substrate having curling resistance and lateral symmetry, wherein the incompatible polymer is selected from the group consisting of polystyrene, polyester, polybutylene terephthalate and mixtures thereof. The method of claim 1, A laminated multilayer film substrate that is curling resistant and transversely symmetric, wherein an incompatible polymer is added in an amount ranging from 1 to 10% by weight of the layers of (a) and (c). The method of claim 1, A laminated multilayer film substrate that is curling resistant and transversely symmetric, with the layer of (a) having diagonal and / or unidirectional micropores. The method of claim 5, A laminated multilayer film substrate that is curl resistant and transversely symmetric, with micropores ranging from 50 to 300 per inch. The method of claim 1, A laminated multilayer film substrate that is curling resistant and transversely symmetric, wherein the layers of (a) and (c) have diagonal and / or unidirectional micropores. The method of claim 1, A laminated multilayer film substrate that is curling resistant and transversely symmetric, wherein both the layers of (a) and (c) further comprise a copolymer polypropylene surface on one or more sides thereof. The method of claim 1, A laminated multilayer film substrate having curling resistance and transverse plane symmetry, wherein the resin of (d) comprises an adhesive containing no solvent. The method of claim 9, A laminated multilayer film substrate having curling resistance and transverse plane symmetry, wherein the resin of (d) comprises polyurethane. The method of claim 1, A laminated multilayer film substrate having curling resistance and lateral symmetry, wherein the resin of (d) comprises a component selected from the group consisting of low density polyethylene and linear low density polyethylene. The method of claim 1, A laminated multilayer film substrate that is curling resistant and transversely symmetric, further comprising (e) a security device between the layers of (a) and (c). The method of claim 12, A laminated multilayer film substrate having curling resistance and transverse plane symmetry, wherein the security device is selected from the group consisting of optically variable devices, magnetic devices, electronic devices, and rare earth element-containing devices. The method of claim 1, A laminated multilayer film substrate that is curl resistant and transversely symmetric, further comprising (e) a security device printed on the layer of (b) prior to lamination with the laminate adhesive resin of (d). The method of claim 8, A laminated multilayer film substrate that is curl resistant and transversely symmetrical, wherein the copolymer polypropylene surface on the outer surface is outer coated with an opaque coating. The method of claim 12, A laminated multilayer film substrate that is curl resistant and transversely symmetric, further comprising a transparent window in the film substrate. The method of claim 1, A laminated multilayer film substrate that is curl resistant and transversely symmetric, in the form of a banknote. The method of claim 1, A laminated multilayer film substrate having curling resistance and transverse plane symmetry, wherein the first direction is the machine direction (MD) and the second direction is the transverse direction (TD). A laminated multilayer film substrate that is curling resistant and cross-sectional symmetric for use in the manufacture of bank notes or security documents, (a) a ratio of already initiated tear resistance greater than 10: 1, having at least 50% by weight of high density polyethylene having an inner surface and an outer surface and having a density of at least 0.94, in a second direction substantially perpendicular to the first direction; An unbalanced biaxially oriented first layer oriented in at least a first direction to a degree at least three times greater than the degree of orientation present; (b) a second direction having an inner surface and an outer surface and containing at least 90% by weight of polypropylene, oriented in at least a first direction at an orientation ratio of at least 4: 1, and substantially perpendicular to the machine direction at an orientation ratio of at least 6: 1; Balanced biaxially oriented second layer; (c) the ratio of tear resistance already disclosed is greater than 10: 1 and comprises at least 50% by weight of high density polyethylene having an inner surface and an outer surface and having a density of at least 0.94 and present in a second direction substantially perpendicular to the transverse direction; An unbalanced biaxially oriented third layer oriented in at least the first direction to a degree at least three times greater than the degree of orientation; And (d) a laminate adhesive resin positioned between the inner surface of the layer of (a) and the inner surface of the layer of (c), wherein The second layer is laminated to the first layer and the third layer such that the first direction of the third layer orientation substantially coincides with the first direction of the first layer orientation, and the layer of (a) is coextruded on its inner surface. A laminated multilayer film substrate that is curling resistant and transversely symmetric, further comprising a propylene copolymer surface. The method of claim 19, A laminated multilayer film substrate having curling resistance and transverse plane symmetry, wherein the first direction is the machine direction (MD) and the second direction is the transverse direction (TD). A laminated multilayer film substrate that is curling resistant and cross-sectional symmetric for use in the manufacture of bank notes or security documents, (a) a first layer having a ratio of tear resistance already disclosed that is greater than 10: 1 and has an inner surface and an outer surface and comprises at least 50% by weight of unoriented and blown high density polyethylene having a density of at least 0.94; (b) a second direction having an inner surface and an outer surface and containing at least 90% by weight of polypropylene, oriented in at least a first direction at an orientation ratio of at least 4: 1, and substantially perpendicular to the machine direction at an orientation ratio of at least 6: 1; A second layer oriented in a direction; (c) a third layer having a ratio of tear resistance already disclosed that is greater than 10: 1 and has an inner surface and an outer surface and comprises at least 50% by weight of unoriented and blown high density polyethylene having a density of at least 0.94; And (d) a laminate adhesive resin positioned between the inner surface of the layer of (a) and the inner surface of the layer of (c), wherein A laminated multilayer film substrate that is curling resistant and transversely symmetrical, wherein the layer of (a) further comprises a co-extruded propylene copolymer surface over its inner surface.